The research of the Johann Heinrich von Thünen Institute (TI) is targeted at developing concepts for a sustainable, ecologically viable, and competitive agriculture and food economy, forestry and wood economy, fisheries and aquaculture. Another main focus is to help overcome the specific problems of the rural areas. The TI is the federal competence for policy and society.
There are a lot of vacancies in the different TI branch institutions. You may find it at http://www.ti.bund.de/de/startseite/aktuelles/stellenangebote.html.
My working place is at the TI fof Wood Research in Hamburg-Bergedorf.
In Baden-Württemberg 17 PhD employments are offered by the Bioeconomics programme ForWerts. The topics are focused on regional Biomass utilization.http://www.bbwforwerts-application.de/
In Göttingen 15 scholarships in different research topics of material science are available!